An investigation of Salm. saint-paul infection in England and Wales in 1959 is described. In one-third of the human incidents the infection was attributed to home-produced meat coming from two infected abattoirs.

Animal infection was demonstrated and was probably due to contaminated imported animal feedingstuffs.

The clinical histories of 55 of the 89 cases reported during the year were studied. There was one death. In ten patients the illness commenced with fever and malaise and diarrhoea was absent or did not occur until 24–48 hr. later. One patient developed meningitis and another an abdominal abscess.

A survey has been made of a sample of children aged 0–5 years in a number of areas in England and Wales for the presence of symptomless excreters of poliomyeitis virus.

The investigation covered a 2-year period from the spring of 1957 to the summer of 1959.

Altogether 28, 797 specimens were examined of which 140 were positive for Type 1 virus, 24 for Type 2, and 44 for Type 3, the corresponding rates being 4·85, 0·83, and 1·53 per 1000 specimens respectively.

It is estimated that for every notified case of poliomyelitis there were about 140 symptoinless excreters of Type 1 virus. No accurate estimates of this ratio were possible for the other two types, but it was certainly much higher.

The incidence of positive specimens was 15 per 1000 in the first and 2·6 per 1000 in the second year of the survey, but there were considerable local variations.

Type 2 virus was not isolated during the second year. Most specimens were examined for the presence of salmonellae and shigellae which both had a frequency of about 2 per 1000. The salmonellae were mainly S. typhimurium, and all the shigellae were Sh. sonnei.

Some information was obtained on the prevalence of other viruses. Coxsackie B virus was the most commonly isolated and in the second year was commoner than poliomyelitis virus. Its seasonal incidence was roughly the same as that of polio myelitis virus.

Adenoviruses were isolated in about 6 per 1000 specimens and were most common in the winter. ECHO viruses were about half as common as adenoviruses and the maximum incidence was in the autumn.

The limitations of the sampling method used and the problems of analysis of the results are discussed.

1. Bacterial infection of amoebic hepatic abscess is a relatively uncommon event.

2. Investigations to demonstrate a possible bactericidal effect of liver pus in vitro indicated that small inocula, especially of young cultures, of Sh. sonnei, Staph. pyogenes and an organism of pseudomonas species were rendered sterile. Organisms such as Esch. coli, Saim. typhi, Saim. typhimurium, Sh. boydii and Strep.faecalis showed a drop in viable count during the first few hours of incubation followed by a logarithmic increase. The strain of A. aerogenes, on the other hand, was not decreased in numbers during the first few hours of incubation and showed a prolonged lag phase followed by a logarithmic increase in numbers. Shigella sonnei, Staph. pyogenes, Sh. boydii and Strep. fascalis attained to maximum population densities which were less than those obtained in control broth tubes and less than those of other organisms in liver pus.

3. It is suggested that secondary bacterial infection of amoebic liver abscess is often endogenous in origin, occurring after primary aspiration due to disinte gration of the lining wall of the cavity, allowing the entrance of portal blood containing organisms from the damaged bowel.

A tissue culture system using chick embryo cells gave bacteria-free vaccinia virus suspensions of sufficient potency to use as a vaccine. Clinical trials with vaccines prepared by this method gave similar results to those with sheep lymph vaccine.

In 1959, 69 cases of aseptic meningitis were admitted to various hospitals in Scotland—all apparently due to a Hitherto unrecognized virus. This agent had the characteristics of an ECHO virus but differed from the 28 ECHO viruses at present recognized. Seventy-five strains of the virus were isolated, and human thyroid and human amnion tissue cultures proved much superior to monkey kidney tissue cultures for its isolation.

Bordetella pertussis instified by the intranasal route into the lungs of mice multiply without difficulty even from small inocula, although B. pertussis is not a natural pathogen for mice and mouse to mouse infection could not be demonstrated. When the initial dose was large the bacilli multiplied until the number in the lungs reached a critical level at which the mouse died. With smaller doses the critical level was never reached; a maximum count was achieved in 10–14 days, after which the number of viable bacilli declined. These smaller doses were consistently non-lethal and the figures for the viable counts when plotted gave curves of typical shape which were called ‘sublethal curves’. The decline corresponded in time with the development of specific immunity. Growth in the lung during the first 4 days of the infection was exponential, the rate of increase in the viable count depending on the size of the inoculum; the smaller the inoculum the faster the increase. With infecting doses at about the critical level, the numbers did not increase during the first 3–4 days, and with larger doses they decreased during the first 2–4 days of infection.

Antiserum given with the inoculum reduced the number of viable organisms in the lung at once. Its effect was short-lived, because after 24 hr. the lung count rose; nevertheless, the initial check on the bacteria had converted a lethal in fection into a sublethal infection.

The growth of virulent strains of Bordetella pertussis in the brains of mice was studied by carrying out viable counts on mice killed at various times during the infection. The results suggested that this system conformed to the general model which postulates that the organisms causing death multiply in vivo at a rate which is constant for all doses and that death is certain to occur when the number of organisms reaches a certain constant figure.

Perhaps the most important factor in this route of infection is the lodgement of the parasite in the host, for if this is accomplished a single organism grows until the lethal level is reached. There is no sublethal infection.

In actively and passively protected mice, the growth of the organism is approximately the same as in unprotected controls for the first 4–5 days. At this time there is a striking change in protected animals and the viable count falls rapidly and progressively and the animals survive. At the same time the blood-brain barrier becomes permeable and circulating antibodies diffuse into the brain. In vitro, specific antisera plus complement are highly bactericidal.

1. The main differences between intracerebral and intranasal infections in mice with virulent strains of Bordetella pertussis are in: (1) the responses to small in fecting doses (< 1 LD 50); (2) the action of antisera in controlling infection; (3) the action of toxin on brain and lung; and (4) the rates of increase of the viable count. The two infections can run concurrently in the same mouse without any demonstrable interference.

2. The terminal viable count in the lung and brain is c. 108 organisms.

3. In the brain there is no sublethal infection with virulent strains; probably even single organisms can grow up to the critical level and kill the mouse. In the lung sublethal infections are found in which the count rises to a figure below the critical level and then declines.

4. The action of ‘intranasal’ antiserum is to reduce a lethal infection to a sublethal one in the lung but there is no effect in the brain. ‘Intracerebral’ antisera cannot act until the blood-brain barrier becomes leaky, when they are able to reduce the viable count and eventually sterilize the brain. In the lung ‘intracerebral’ sera have no action against lethal infections but can control small infections (<I LD 50). The sublethal intranasal test measures this effect but it also measures the action of ‘intranasal’ sera and so cannot be used to distinguish the two types of sera and hence the two antigens.

1. The existing procedures recommended for the detection of carriers of enteric pathogens are reviewed.

2. The techniques employed in this work at present were re-examined.

3. An investigation of the sera of 67 chronic typhoid carriers and 343 normal persons, suggested that titrations for typhoid Vi, O and H agglutinins are useful screening tests for the detection of typhoid carriers. The examination may be usefully extended to the titration of H agglutinins against paratyphoid B and paratyphoid A, the former as a possible indicator of the carriage of Salm.paratyphid B, the latter as an indicator of previous inoculation with T.A.B. vaccine.

4. Inoculation did not appear to increase the proportion of positive reactions with TVi bacterial suspension, which in uninfected persons was about 1%. In contrast, the proportion of positive reactors with TO suspension rose from 8·8% in uninoculated to 25·3% in inoculated persons, at a serum dilution of 50; and with TH suspension the positive figure rose from 2·7% in uninoculated to 71·4% in inoculated persons at a serum dilution of 25. Inoculation thus impairs the value of TO agglutination and destroys that of TH agglutination as indicators of infection.

5. The investigation of 29 chronic carriers showed that a single bacteriological examination of excreta for the presence of Salm. typhi is not a reliable method of carrier detection. Increasing the number of specimens to three greatly raises the probability of detection.

6. The findings are discussed and a revised form of paragraph 5 of the Ministry of Health Memorandum on the safeguards recommended for adoption by water undertakings is suggested.

The Working Party is grateful to a number of pathologists for the supply of sera from chronic carriers and we should also like to thank Mr F. J. Flyn of the Central Enteric Reference Laboratory for his great technical help.

It has been found that antigens suitable for routine tests for complement-fixing or precipitating antibodies in the sera of suspected cases of chickenpox or zoster can be readily prepared from tissue cultures of human amnion infected with zostervaricella virus.

Useful antigens were obtained when infected cells were incubated at 36°–38° C. in bovine amniotic fluid diluted with an equal volume of Hanks' solution.

Virus strains gave a good yield of antigen after two or more passages in tissue culture but one strain in its fiftieth passage did not.

Harvested culture fluids require 5- to 20-fold concentration for complement-fixation tests and 100- to 200-fold for precipitation tests; concentration of culture fluids was readily effected by drying from the frozen state after removal of salts by dialysis. Tissue culture antigens gave results by complement-fixation tests which were comparable to those given by a good vesicle fluid.

Some evidence was obtained that the antigens responsible for precipitation were not identical with those fixing complement with convalescent sera.

The method of multi-regression analysis as applied to data which are classified in a non-metric manner is discussed, and a set of data relating the risk of post-operation sepsis to various factors is analysed in this way.

Age over 60, male sex, long duration of operation, incision over 6 in. long and the insertion of a drain in the wound are all found to be associated with increased risk of post-operative sepsis. Operations for appendicectomy and those on the gall bladder have a relatively high basic risk of developing sepsis while operations for gastrectomy or those on the thyroid, and probably thoracic operations, have a low basic risk. The substantial differences in the gross risk of post-operative sepsis associated with the operations performed in the different hospitals included in the analysis are shown to be almost entirely accounted for by differences in the operations performed in them.